Rotary underreamer



N. D. FOSTER ROTARY UNDERREAMER Dec. 22, 1931.

Filed Jan. 26, 1927 INVENTOR. /V0fi/ Q 552%.?" WwZZZ/au z Wd/m,

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J and corresponding Patented Dec. 22, 1931 UNITED STATES PATENT OFFICE NOBLE D. FOSTER, OF WHITTIEB, CALIFORNIA, ASSIGNOR, BY IlJ IBiEGT AND EESNE AS- SIGNMENTS, OF THBEE-FOURTHS TO JOHN W. MACCLATCHIE, OF COMPTON, CALI- FORN'IA ROTARY UNDERREAMER Application flled January 26, 192:7. Serial No. 163,655.

. cutters, mounted so as to be urged .to projected or expanded position by rotation of w underreamer body due to centrifugal action and whereby a resistance to cutting in one direction will tend to hold and maintain the cutters projected. To this end, rotary cutters are mounted on the body so that one j ournal thereof will be moved automatically outward int'o projected position.

These objects together with other objects accomplishments are obtained by means 0 the embodiment of my invention, illustrated in the accompanying drawings, in which:

Fig. l is an elevation of an underreamer; Fig. 2 is a section as seen on line 2-2 of Fig. 1; I

Fig. 3 is an axial section througha fragment of the underreamer showing a cutter in ex panded position; and Fig. 4 is a fragmentary section of a modified form of underreamer.

Referring more particularly to the draw- 4 ings, the bodyof the tool is shown having a mandrel portion 10 with an annular recess providing upper and lower ledges 11 and 12 respectively. This recess serves for accommodating the cutters in retracted position. There are three cutters shown herein, although a greater or lesser number may be used. Suitable water courses for circulation of fluid may be provided.

At the upper end of the body 10 is a threaded tapered in 13 arran ed to receive a cap 14:, the cap orming in e set a portion of the body and having a tapered threaded pin 9 forconnection to the tool string.

\ Extendingto the body at ledge 11 are holes to receive pins 15. The pins are provided with heads and are removable and insertable when the cap 14 is detached. Arms 16 are pivotally mounted upon the pins 15, being provided with heels 17 to abut against the mandrel portion 10 of the body.

J ournalled in each' arm 16 is the upper trunnion of a roller 18. The lower trunnion of each roller 18 may be journalled in aself aligning bearing mounted in the ledge 12 as shown in Figs. 1 and 2. This hearing may consist of a ball 19 mounted in a suitable socket. The ball is mounted in a recess in the ledge. When one arm of a cutter is positioned so as to extend outwardly, the roller journalled therein will tilt outwardly into projected position as shown in Fig. 3. When the arm is in its outermost position, the extension or heel 17 will rest against the man- .drel 10 and prevent the arm from being swung further towards the rear. It is obvious that the invention is not limited to the use of an arm 16 for swinging the roller outwardly, but other means may be employed. The rearward upper edge of the arm is rounded as indicated by 20 so that when engaged with the shoe of a casing or like tubular member, and the tool is moved upwardly, there will be a tendency to swing the arm inwardly and retract the cutter.

In Fig. 4, the roller 18 has its trunnions 21 and 22 slightly tapered, and the lower trunnion is disposed in a bushing 23. This construction permits the roller to tilt and swing.

The cutters are placed in their retracted position as shown in Fig. 1 and inserted through the casin until they are positioned below the shoe. i rotation of the tool in a right hand direction will, due to centrifugal action tend to resolve or throw the cutters into their projected position. As the cutters are moved outwardly, they will engage a side of the hole and the resistance encountered will aid in moving the cutters backwardly and swinging-the arms to their full outer 1 accommodate a cutter in retracted position,

a rotary cutter journalled at its lower end in said body by a self aligning bearing stationary in relation to the drilling axis of said underreamer, an arm pivotally secured to said body for swinging outwardly and having the upper end of said cutter journalled therein, whereby said cutter may freely swing outwardlyto incline the latter in projected position.

2. An underreamer comprising a body having a recess in its outer surface adapted to accommodate a cutter in retracted position, a cutter journalled at one end in said body by a self-aligning bearing, an arm pivotally secured to said body for swinging outwardly and having the other end of said cutter journalled therein, the axis of said cutter ranging lengthwise of the drilling axis of the underreamer whereby said cutter may freely swing outwardly to incline the latter in projected position, said arm having an abutment engageable with said body to limit the rearward movement.

3. An underreamer of the character described comprising a body, a cutter movably mounted thereon having a structural axis one end of said axis being swivelled about a point fixed with respect to said body and the other end being secured to and movable to and from the drilling axis of said body.

4. An underreamer of the character described comprising a body, a cutter movably mounted thereon having a structural axis one end of said axis being swivelled about a point fixed with respect to said body, an arm extending laterally of the drilling axis of said body and pivotally secured to said body, the other end of said axis being secured to said arm.

In witness that I claim the foregoing I have hereunto subscribed my name this 20th day of January, 1927.

NOBLE D. FOSTER.

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